No prior art search was conducted on the subject matter of this application in U.S. Patent and Trademark Office or in any other search facility.
In vision units which are used in motor vehicles it is often necessary to provide a visual barrier along a part of the vision unit so that when the vision unit is in its installed position, one may not view areas of the motor vehicle which should not be viewed. For example, the windshields installed in modern motor vehicles extend generally down below the top of an instrument panel which is located inside the windshield. If the windshield was completely transparent in this area, one could look from the exterior of the vehicle and see the equipment mounted underneath the instrument panel. Thus a visual barrier is applied to the lower edge of the windshield in order to provide a means of blocking the path of vision into the area below the instrument panel.
In the same manner, an opaque border is provided around the rear vision unit or backlite of the motor vehicle. The border is used so that one cannot see the area below the package tray or areas behind the molding which secure the backlite in its proper position.
In the past, these visual barriers have been applied to the vision unit in question during the manufacture of that vision unit. Generally, the vision barriers have been applied in the necessary area by silk screen printing a paste of a material consisting of a fusable ceramic material and a pine oil onto the vision unit. The vision unit is then heated in a heating lehr in order to burn off the pine oil and fuse the ceramic frit to the vision unit. The ceramic frit is opaque and thus provides the vision barrier.
Since the pine oil/ceramic frit paste is still flowable after it has been applied to the vision unit, the unit must be handled very carefully while it is moved from the silk screen printing operation to any other operation. If the paste is contacted or touched, it may be smeared or wiped over the surface of the vision unit thereby ruining that unit. If the paste material is smeared or smudged along the vision unit, it is necessary to wash all of the material off that vision unit and re-process the same through the silk screen printing operation.
Since the silk screen printing operation is normally along the lower edge or around all of the edges of the vision unit, it is sometimes quite difficult to handle that vision unit with the smearable paste material thereon without, in fact, smearing that paste. Thus, there has been in the prior art substantial difficulty in manufacturing vision units with opaque screens along the edges thereof because of the fact that the paste which is used to form the opaque area is a paste material which may be smudged during the handling of the vision unit.
It is a principal object of the method of this invention to provide a method in which a paste applied to define an opaque area on a vision unit is a radiation curable paste and that paste is radiation cured prior to handling so that upon handling the same cannot be smudged.